An antenna used in 5G communication requires a structure having a low loss characteristic and a high directivity due to the losses in the millimeter band.
A microstrip patch array antenna, a box-shaped horn array antenna, and so on, have been used as a conventional antenna for use in the millimeter band. However, the microstrip patch array antenna has a high level of difficulty in transmitting signals having the same amplitude to each radiation slot and a high loss rate caused by the material. Also, the box-shaped horn array antenna has a complicated structure and is difficult to manufacture.
Thus, a development of an antenna capable of transmitting radio wave signals in the millimeter band with minimal losses and capable of being easily manufactured is necessary.